Fix zero-sized blur with crop rect.

src/effects/SkBlurImageFilter.cpp

 /*
  * Copyright 2011 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkBlurImageFilter.h"
 #include "SkColorPriv.h"
 #include "SkDevice.h"
 #include "SkGpuBlurUtils.h"
 #include "SkOpts.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #if SK_SUPPORT_GPU
 #include "GrContext.h"
 #include "SkGr.h"
 #endif
 
 // This rather arbitrary-looking value results in a maximum box blur kernel size
 // of 1000 pixels on the raster path, which matches the WebKit and Firefox
 // implementations. Since the GPU path does not compute a box blur, putting
 // the limit on sigma ensures consistent behaviour between the GPU and
 // raster paths.
 #define MAX_SIGMA SkIntToScalar(532)
 
-static SkVector mapSigma(const SkSize& localSigma, const SkMatrix& ctm) {
+static SkVector map_sigma(const SkSize& localSigma, const SkMatrix& ctm) {
     SkVector sigma = SkVector::Make(localSigma.width(), localSigma.height());
     ctm.mapVectors(&sigma, 1);
     sigma.fX = SkMinScalar(SkScalarAbs(sigma.fX), MAX_SIGMA);
     sigma.fY = SkMinScalar(SkScalarAbs(sigma.fY), MAX_SIGMA);
     return sigma;
 }
 
 SkBlurImageFilter::SkBlurImageFilter(SkScalar sigmaX,
                                      SkScalar sigmaY,
                                      SkImageFilter* input,
@@ skipping 44 matching lines @@
     }
 
     SkIRect srcBounds, dstBounds;
     if (!this->applyCropRect(this->mapContext(ctx), src, srcOffset, &dstBounds, &srcBounds)) {
         return false;
     }
     if (!srcBounds.intersect(dstBounds)) {
         return false;
     }
 
-    SkAutoLockPixels alp(src);
-    if (!src.getPixels()) {
-        return false;
-    }
-
-    SkAutoTUnref<SkBaseDevice> device(proxy->createDevice(dstBounds.width(), dstBounds.height()));
-    if (!device) {
-        return false;
-    }
-    *dst = device->accessBitmap(false);
-    SkAutoLockPixels alp_dst(*dst);
-
-    SkVector sigma = mapSigma(fSigma, ctx.ctm());
+    SkVector sigma = map_sigma(fSigma, ctx.ctm());
 
     int kernelSizeX, kernelSizeX3, lowOffsetX, highOffsetX;
     int kernelSizeY, kernelSizeY3, lowOffsetY, highOffsetY;
     getBox3Params(sigma.x(), &kernelSizeX, &kernelSizeX3, &lowOffsetX, &highOffsetX);
     getBox3Params(sigma.y(), &kernelSizeY, &kernelSizeY3, &lowOffsetY, &highOffsetY);
 
     if (kernelSizeX < 0 || kernelSizeY < 0) {
         return false;
     }
 
     if (kernelSizeX == 0 && kernelSizeY == 0) {
-        src.copyTo(dst, dst->colorType());
-        offset->fX = dstBounds.x() + srcOffset.x();
-        offset->fY = dstBounds.y() + srcOffset.y();
+        src.extractSubset(dst, srcBounds);
+        offset->fX = srcBounds.x();
+        offset->fY = srcBounds.y();
         return true;
     }
 
+    SkAutoLockPixels alp(src);
+    if (!src.getPixels()) {
+        return false;
+    }
+
+    SkAutoTUnref<SkBaseDevice> device(proxy->createDevice(dstBounds.width(), dstBounds.height()));
+    if (!device) {
+        return false;
+    }
+    *dst = device->accessBitmap(false);
+    SkAutoLockPixels alp_dst(*dst);
+
     SkAutoTUnref<SkBaseDevice> tempDevice(proxy->createDevice(dst->width(), dst->height()));
     if (!tempDevice) {
         return false;
     }
     SkBitmap temp = tempDevice->accessBitmap(false);
     SkAutoLockPixels alpTemp(temp);
 
     offset->fX = dstBounds.fLeft;
     offset->fY = dstBounds.fTop;
     SkPMColor* t = temp.getAddr32(0, 0);
@@ skipping 51 matching lines @@
         *dst = src;
     }
 
     dst->outset(SkScalarMul(fSigma.width(), SkIntToScalar(3)),
                 SkScalarMul(fSigma.height(), SkIntToScalar(3)));
 }
 
 void SkBlurImageFilter::onFilterNodeBounds(const SkIRect& src, const SkMatrix& ctm,
                                            SkIRect* dst, MapDirection) const {
     *dst = src;
-    SkVector sigma = mapSigma(fSigma, ctm);
+    SkVector sigma = map_sigma(fSigma, ctm);
     dst->outset(SkScalarCeilToInt(SkScalarMul(sigma.x(), SkIntToScalar(3))),
                 SkScalarCeilToInt(SkScalarMul(sigma.y(), SkIntToScalar(3))));
 }
 
 bool SkBlurImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const Context& ctx,
                                        SkBitmap* result, SkIPoint* offset) const {
 #if SK_SUPPORT_GPU
     SkBitmap input = src;
     SkIPoint srcOffset = SkIPoint::Make(0, 0);
     if (!this->filterInputGPU(0, proxy, src, ctx, &input, &srcOffset)) {
         return false;
     }
     SkIRect srcBounds, dstBounds;
     if (!this->applyCropRect(this->mapContext(ctx), input, srcOffset, &dstBounds, &srcBounds)) {
         return false;
     }
     if (!srcBounds.intersect(dstBounds)) {
         return false;
     }
-    GrTexture* source = input.getTexture();
-    SkVector sigma = mapSigma(fSigma, ctx.ctm());
+    SkVector sigma = map_sigma(fSigma, ctx.ctm());
+    if (sigma.x() == 0 && sigma.y() == 0) {
+        input.extractSubset(result, srcBounds);
+        offset->fX = srcBounds.x();
+        offset->fY = srcBounds.y();
+        return true;
+    }
     offset->fX = dstBounds.fLeft;
     offset->fY = dstBounds.fTop;
     srcBounds.offset(-srcOffset);
     dstBounds.offset(-srcOffset);
     SkRect srcBoundsF(SkRect::Make(srcBounds));
-    SkAutoTUnref<GrTexture> tex(SkGpuBlurUtils::GaussianBlur(source->getContext(),
-                                                             source,
+    GrTexture* inputTexture = input.getTexture();
+    SkAutoTUnref<GrTexture> tex(SkGpuBlurUtils::GaussianBlur(inputTexture->getContext(),
+                                                             inputTexture,
                                                              false,
                                                              SkRect::Make(dstBounds),
                                                              &srcBoundsF,
                                                              sigma.x(),
                                                              sigma.y()));
     if (!tex) {
         return false;
     }
     GrWrapTextureInBitmap(tex, dstBounds.width(), dstBounds.height(), false, result);
     return true;
 #else
     SkDEBUGFAIL("Should not call in GPU-less build");
     return false;
 #endif
 }
 
 #ifndef SK_IGNORE_TO_STRING
 void SkBlurImageFilter::toString(SkString* str) const {
     str->appendf("SkBlurImageFilter: (");
     str->appendf("sigma: (%f, %f) input (", fSigma.fWidth, fSigma.fHeight);
 
     if (this->getInput(0)) {
         this->getInput(0)->toString(str);
     }
 
     str->append("))");
 }
 #endif